Laser seeker test set

ABSTRACT

A target simlator comprising a sequencing infrared source and a plurality of binary coded inputs is used to test the reaction of a missile seeker which operates on the principal of a parabolic mirror being flooded with parallel light rays which in turn are reflected onto the detector. The light rays are either parallel to the center line axis of the missile or at some angle thereto. The angle of these rays with respect to the missile centerline is detected by the missile guidance system to cause the missile to track the rays. The target simulator according to the present invention utilizes this principle without flooding the entire mirror using a 1/4 inch column of parallel light rays from sequenced infrared sources.

United States Patent [191 LaGrange et al.

[451 Dec.24, 1974 LASER SEEKER TEST SET [75] Inventors: Don E. LaGrange,Los Angeles;

Edward J. Davis, China Lake; Eugene R. Sheer, Ridgecrest; Ralph E.Brewer, Ridgecrest; Curtis A. Hamilton, Ridgecrest, all of Calif.

[73] Assignee: The United States of America as represented by theSecretary of the Navy, Washington, DC.

[22] Filed: Oct. 26, 1973 [21] Appl. No.: 409,996

[52] US. Cl. 250/495, 73/1 F, 244/316 [51] Int. Cl. G2lh'5/00 [58] Fieldof Search 250/495, 504, 338, 340,

250/349; 102/38; 244/316, 14; 343/17.7; 356/152; 273/98, 101, 105.3;240/1 A; 40/130 R; 73/1 R, 1 F; 219/553 [56] References Cited UNITEDSTATES PATENTS 3,227,879 H1966 Blau et al 219/553 X SWITCH pow R LOGICSUPl LY Cragin et al. 250/495 X Moser 250/340 [57] ABSTRACT A targetsimlator comprising a sequencing infrared source and a plurality ofbinary coded inputs is used to test the reaction of a missile seekerwhich operates on the principal of a parabolic mirror being flooded withparallel-light rays which in turn are reflected onto the detector. Thelight rays are either parallel to the centerline axis of the missile orat some angle thereto. The angle of these rays with respect to themissile centerline is detected by the missile guidance system to causethe missile to track the rays. The target simulator according to thepresent invention utilizes this principle without'flooding the entiremirror using a inch column of parallel light rays from sequencedinfrared sources.

8 Claims, 6 Drawing Figures 3o PANEL Patented Dec. 24, 1974 3,857,042

5 Sheets-Sheet 1 l2 IO r E SWITCH POWER TEST '30 LOGIC SUPPLY PANEL Fig.i

atented Dec. 24, 1974 5 Sheets-Sheet 2 Patented Dec. 24, 1974 3,857,042

5 Sheets-Sheet 5 Patented Dec. 24, 1974 3,857,042

5 Sheets-Sheet 4 LASER SEEKER TEST SET BACKGROUND OF THE INVENTION Thisinvention relates to testing systems and more particularly to targetsimulating systems for testing tracking apparatus. More particularly theinvention relates to the simulation of moving target reflected radiationto test laser guided missile seekers before flight.

As missile guidance and control systems become more sophisticated, theprice of the missile rises and it is increasingly important to test theguidance and control system thoroughly before certifying the missile touse. It is especially advantageous to be able to final test on theaircraft. The target simulator and test equipment according to thepresent invention is designed to ensure that the guidance and controlsystem of a laser guided missile, for example, is in proper workingorder. The system may be used with the missile before delivery to alaunching vehicle or may be adapted for use with the missile in place onthe aircraft.

SUMMARY OF THE INVENTION By visually observing either the seeker headactivity or instrumentation attached to the missile, the capability ofthe seeker tracking unit can be'determined before flight. This may beaccomplished with the missile attached to the aircraft by observing theinstrumentation in the aircraft. I

The'test equipment may be arranged in a housing which can be quickly andsecurely fixed to a missile nose section in a predetermined positionwith respect to the seeker unit.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING FIG. 1 is adiagrammatic view constituting a schematic illustration of a systemaccording to the invention;

FIG. 2 is an exploded view of one embodiment of a target simulatoruseable with the system of FIG. 1;

FIG. 3.is a plan view of the diode carrier of FIG. 2;

FIG. 4 is a side elevational view of the carrier of FIG. 3 partly insection;

FIG. 5 is an enlarged cross sectional view taken along line V-V of FIG.3; and

FIG. 6 is a simplified diagram of a switching logic circuit useable withthe system.

DESCRIPTION AND OPERATION As shown in FIG. I, the test arrangement 10comprises a target simulator l2 aligned with the nose section l4 of aguided missile, for example, on a test stand 15. The simulator 12comprises a linear array 13 of small light-emitting diodes l7 actuatedby driver circuitry 16 under the control of logic circuit means 18.

When any ofthe diodes 17 in array 13 are illuminated, they emit infraredrays (represented by broken line) which are beamed through the window 20of nose section l4 and these rays impinge on a toroidal parabolicprimary mirror 24 which focuses the rays on a secondary mirror 26 whichin turn reflects the rays to detector means 28. Detector means 28generates pulses in accordance with directional parameters of thereceived radiation. The pulses generated are then applied to the missilelogic section 29 in the nose section of the missile.

In the arrangement shown in FIG. 1, the output of the logic circuitry 29is indicated on a test panel 30. When the unit is usedin the field,however, the indication may be exhibited on a cockpit display panel, forexample, in an aircraft. The target simulator 12 is connected toswitching logic circuitry 18 through which the diodes 17 may besequentially illuminated to simulate rays emanating from a movingtarget. A power supply 32 and an oscillator 34 supply the necessarycurrent to the simulator.

The detector 28 is a' four quadrant IR detector which is affected by theangle in which the rays are received. The missile seeker system beingtested is designed to correct for the amount of deviation of the beamangle from the missile seeker line axis.

The target simulator 12 comprises a sequencing infrared source that usesfive binarycoded inputs to select the desired target. One input isutilized to select either azimuth or elevation and the other four inputsare used to select infrared sources from l0 to +10 in 2 conditions inthat the target simulator 12 does not flood the entire mirror area butuses only a one quarter inch column of parallel light'rays. The resultsand the reaction of the missile tracking system 29, however, is thesame. The light emitting diodes 17 are actuated by diode drivers 16inresponse to signals from switching logic panel 18. I

The diodes 17 may be arranged in orthogonal linear array or any otherdesired pattern within the viewing envelope of the missile.

In addition to the laboratory type arrangement of FIG. 1, the diodearray may be fastened directly to the missile nose 14, shown in FIG. 2.The nose of the missile has an annular groove 35 which may be used tofasten the diode carrier36 using a split collar 38 and an adaptor 40.The collar 38 has an internal contour 39 complementary to the contour ofthe missile nose at groove 35.

The collar is installed around nose 14 of the missile at groove 35 andfastened by means of a clamp 41. The collar carries three similar clampmembers 42 designed to interact with hooks 43 on adapter 40. When thusconnected, the collar and adaptor form a hollow integral light shieldaround missile window 20.

The diode carrier 36 is fastened in place in the forture frompenetrating under the cover 44 when the unit is assembled. In practice,the diode carrier 36 remains assembled to the adaptor 40 with the cover44 in place unless disassembly is necessary, for example, for repair.

A preferred arrangement of the diodes in carrier 36 is shown in FIG. 3.Although a simple orthogonal intersecting pattern was usedsatisfactorily in early models, the diode array shown in FIG. 3 has beenfound to be more versatile, covering a greater area of the missileoptics with a minimum size of the diodes array.

It will be noted that only the diode mounted in hole K1 will be onboresight parallel to the missile axis. The remainder of the diodes aremounted in holes in four rows forming roughly the sides of a squaresuperimposed on the torroidal field of view of the missile optics at theclose range of the test unit. The row of holes M1 through M is typicaland the angular placement of the holes is more clearly shown in FIG. 5.FIG. 3 also shows four holes used for mounting the carrier to adaptor 40and one hole 46 which mates with a locator pin (not shown) to ensureproper alignment of carrier and adaptor during assembly.

FIG. 4 shows the shape of carrier 36 and the O ring groove 47 around theperiphery.

FIG. 5 shows the boresight diode hole K1 and the holes Ml through M5ranging from 2 to angle to boresight. The rows N, H and J shown in FIG.3 are similarly arranged with respect to boresight and two imaginarylines X and Y orthogonally intersecting the line of boresight. In thetable below the legend to 'X indicates deviation from boresightaTongline X and to Y means that deviation from boresight along line Y.

HOLE DATA HOLE SYMBOL The diodes l7 fit into the holes and are heldagainst a shoulder 48 by a compression spring 50 which is held in placeby a lock ring 52 fitted into a groove 53 in the side wall of the hole.The electrical leads 54 of the diodes are led through the center ofsprings 50 to connection boards (not shown) which may be fastened to thesurface of carrier 36. The electrical system of target simulator 12 isschematically shown in FIG. 6.

The power supply 32 furnishes power to the system through a Masterswitch 54 and a series of control switches shown on the left hand sideof the FIG. 6 diagram.

Switches 55, 56 and 57 may be used to manuallyselect either the +2 diodeM1, the 0 diode Kl or the -2 diode H1 respectively, for example, toalign the test set with the missile system. Switch 58 selects thedirection of sequencing of the diodes. The reset & function actuateswitch 59 is a three-position switch, normally open, and may bepositioned in the function actuate or in the reset position as desired.To actuate the test arrangement, switch 59 is placed in its lower orfunction actuate position. When switch 59 is moved to the reset or upperposition, the system returns to a condition in which the l0 diode H5 isON (See FIG. 3).

The automatic-manual switch 60 is normally in the automatic mode but maybe switched to the lower or manual position as desired.

The diode ON/OFF switch 61 is provided so that the light emitting diodesmay be turned off leaving the remainder of the system on standby.

Selection is made through the operation of an Up- Down Counter 62 and aDecoder 64 with associated flip flops 66, 68 ythrough logic NAND gates70-76 and AND gates 80, 82 and 84.

When the Diode ON/OFF switch, 61, is placed in the lower position inFIG. 2, voltage (Logic ONE) is supplied to inhibit decoder 64. If theautomatic-manual switch 60 is in the upper position as shown, a logicONE will be supplied to the NAND Gates 74 and 76. With the Left-to-Rightand Right-to-Left switch 58 in the upper position as shown, a logic ONEwill be supplied to NAND gate 71 and AND gate 82. At the same time'switch 58 places a Logic Zero on-NAND gate 70 and AND gate 84. Alsowith switches 55, 56 and 57 in position shown, a logic ONE will besupplied to input terminal C of the up-down counter 62 and terminals, A,B and C will be at ZERO.

Desiring now to actuate the mechanism, if the Resetactuate switch 59 beplaced in the lower position, then a logic ONE will be supplied to flipflop (one shot) 68.

When the decoder 64 is at rest, the outputs to the diode drivers 16 andto NAND gate 72 is at a logic ZERO. A logic zero on NAND gate 72 causesa logic ONE output which enables theiAND gate 82 which puts a logic ONEon NAND gate 75 allowing the clock pulse from the oscillator to carrythrough. Since 74 and 76 were already enabled there is an output signalfrom 76 of alternating ONE-ZERO going to AND Gate 80, which has a logicONE applied to the other terminal, as related above. Thus we get a logicONE-ZERO altemating from AND gate 80 going to NAND gate 70. The otherterminal of gate 70 has already been enabled as stated above, analternating ONE-ZERO signal goes to the up-down counter 62. The counter62 then starts counting in one direction or the other and signals arepresented to the decoder 64. These signals cause the decoder 64 tostart'outputting signals from eleven out put terminals in sequence tovarious terminals of diode drivers 16.

These signals from decoder 64 in turn activate diode drivers 16 throughenabling circuitry to light up the light emitting diodes in sequence.When the last light emitting diode is illuminated in the right to leftdirection, the system comes to'rest with the output terminals of decoder64 in a ZERO condition and, in order to start the system again, theLeft-Right switch must be changed to its opposite position and theFunction Actuate switch again depressed.

What is claimed is:

1. Target simulating apparatus for investigating operational efficiencyof a light energy sensitive tracking system having a finite viewingenvelope;

said target simulating apparatus including;

a plurality of illuminable elements arranged to emit radiant energywaves toward said tracking system within the viewing envelope of saidsystem;

means for individually illuminating selected ones of said elements; and

means for illuminating said elements in timed sequence.

2. The apparatus of claim 1 wherein said elements are arranged in aplane orthogonal to the longitudinal axis of said viewing envelope andeach element, when illuminated, emits radiation in a particularprearranged angular direction in relation to said axis.

3. The apparatus of claim 2 wherein said elements are arranged in aplurality of linear arrays forming roughly a square having sidesapproximately equidistant from said axis. 1

4. The apparatus of claim 3 wherein said angular relationship varies:

a. along a first side of said square from 0 to in a first direction(x);

b. along a second side from 2 to 10 in a second direction (y) orthogonalto said first direction;

c. along a third side from 2 to 10 in said direction (x); and d. alongthe fourth side from 2 to 10 in said direction (y).

5. The apparatus of claim 4 wherein said elements are electricallyexcitable infrared radiating devices and said means for illuminatingsaid elements includes a source of'regular electrical pulses of apredetermined frequency and electrical logic circuitry for controllingapplication of current to said devices.

6. The apparatus of claim 3 wherein said elements are electricallyexcitable infrared radiating devices and said means for illuminatingsaid elements includes a source of regular electrical pulses of apredetermined frequency and electrical logic circuitry for controllingapplication of current to said devices.

7. The apparatus of claim 2 wherein said elements are electricallyexcitable infrared radiating devices and said means for illuminatingsaid elements includes a source of regular electrical pulses of apredetermined frequency and electrical logic-circuitry for controllingapplication of current to said devices.

8. The apparatus of claim 2 wherein said elements are arranged in aplurality of linear arrays and wherein said angular direction for diodesin each array range from 2 to 10 and one additional element arranged toemit rays essentially parallel to said axis.

1. Target simulating apparatus for investigating operational efficiencyof a light energy sensitive tracking system having a finite viewingenvelope; said target simulating apparatus including; a plurality ofilluminable elements arranged to emit radiant energy waves toward saidtracking system within the viewing envelope of said system; means forindividually illuminating selected ones of said elements; and means forilluminating said elements in timed sequence.
 2. The apparatus of claim1 wherein said elements are arranged in a plane orthogonal to thelongitudinal axis of said viewing envelope and each element, whenilluminated, emits radiation in a particular prearranged angulardirection in relation to said axis.
 3. The apparatus of claim 2 whereinsaid elements are arranged in a plurality of linear arrays formingroughly a square having sides approximately equidistant from said axis.4. The apparatus of claim 3 wherein said angular relationship varies: a.along a first side of said square from 0* to 10* in a firstdirection(x); b. along a second side from 2* to 10* in a seconddirection (y) orthogonal to said first direction; c. along a third sidefrom 2* to 10* in said direction (x); and d. along the fourth side from2*to 10* in said direction (y).
 5. The apparatus of claim 4 wherein saidelements are electrically excitable infrared radiating devices and saidmeans for illuminating said elements includes a soUrce of regularelectrical pulses of a predetermined frequency and electrical logiccircuitry for controlling application of current to said devices.
 6. Theapparatus of claim 3 wherein said elements are electrically excitableinfrared radiating devices and said means for illuminating said elementsincludes a source of regular electrical pulses of a predeterminedfrequency and electrical logic circuitry for controlling application ofcurrent to said devices.
 7. The apparatus of claim 2 wherein saidelements are electrically excitable infrared radiating devices and saidmeans for illuminating said elements includes a source of regularelectrical pulses of a predetermined frequency and electricallogic-circuitry for controlling application of current to said devices.8. The apparatus of claim 2 wherein said elements are arranged in aplurality of linear arrays and wherein said angular direction for diodesin each array range from 2* to 10* and one additional element arrangedto emit rays essentially parallel to said axis.